s = "天才朱序"
print(s[0])
print(s[-1])

s1 = "天才朱序,左手黄子阳，村长闫永强"
print(s1[3:6])

print(s1[::-1])

s2 = "abcdefghijklmnopqrstuzwxyz"
print(s2[2:11:2])

s3 = "abcde"
s4 = s3.capitalize()
print(s4)
print(s3)

s4 = "ABCD,EFG,HIJKLMN"
print(s4.lower())

s5 = "i have  a dream"
print(s5.upper())

#忽略大小写进行判断
a = "abC"
b = "Abc"
if a.upper() == b.upper():
    print("正确")
else:
    print("不正确")